Optical disk

ABSTRACT

Disclosed is an optical disk. The present invention includes a plate having a first area enabling to record information thereon and a second area unable to record the information thereon and a projection on the second area of the plate. Accordingly, the present invention enables to form a protecting layer having a uniform thickness thereon.

[0001] This application claims the benefit of the Korean Application No. P2002-54603 filed on Sep. 10, 2002, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an optical disk.

[0004] 2. Description of the Related Art

[0005] Recently, optical disks having various structures have been developed to improve their recording density. The currently-used optical disks of high density include DVD-R, DVD-RAM, and the like.

[0006]FIG. 1 and FIG. 2 illustrate diagrams of a high-density optical disk according to a related art. Referring to FIG. 1 and FIG. 2, an optical disk includes a disk 20 having a thickness of 1.2 mm and a diameter of 120 mm and a via hole formed at a central portion of the disk 20.

[0007] In this case, a circumference of the disk 20 has a recording layer 10 and the central portion of the disk 20 has the via hole instead of the recording layer 10.

[0008] A diameter of the via hole is about 15 mm, and a diameter of the central portion is about 44 mm.

[0009] And, the recording layer 10 is formed at a location about 0.1 mm far from a surface of the disk 20 on which a light is incident.

[0010] Moreover, a protecting layer 30 is formed on the recording layer 10 to protect the recording layer 10. The protecting layer 30 is formed by attaching a transparent plastic film such as a polycarbonate sheet to the recording layer 10 or spin-coating a UV-hardening resin on the recording layer 10.

[0011] Spin coating on the protecting layer 30 is explained as follows.

[0012] First of all, a UV-hardening resin of liquid state is dropped on the recording layer adjacent to the central portion of the disk. Secondly, the disk is revolved to have the UV-hardening resin coated thereon from the central portion to the circumference by a centrifugal force. Finally, the UV-hardening resin coated on the disk is hardened by UV rays.

[0013] However, Spin coating, as shown in FIG. 3, fails to make the UV-hardening resin formed uniform on the recording layer 10. Namely, a thickness of the UV-hardening resin formed on the recording layer 10 becomes thicker from the center to the circumference of the disk.

[0014] Hence, the thickness deviation of the protecting layer 30 brings about the problem of failing to record/read the information on/from the recording layer 10.

SUMMARY OF THE INVENTION

[0015] Accordingly, the present invention is directed to an optical disk that substantially obviates one or more problems due to limitations and disadvantages of the related art.

[0016] An object of the present invention is to provide an optical disk enabling to form a protecting layer having a uniform thickness thereon.

[0017] Another object of the present invention is to provide an optical disk enabling to facilitate a fabricating process thereof.

[0018] Another object of the present invention is to provide an optical disk enabling to protect a disk surface.

[0019] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0020] To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, an optical disk according to the present invention includes a plate having a first area enabling to record information thereon and a second area unable to record the information thereon and a projection on the second area of the plate.

[0021] Preferably, the projection has at least one inclined lateral side.

[0022] More preferably, a flank angle of the projection is 90˜160°.

[0023] Preferably, the projection is formed on an entire surface of the second area or a portion of the second area.

[0024] Preferably, a surface of the projection is higher than that of the first area of the plate.

[0025] Preferably, a height of the projection is 0.1˜0.6 mm.

[0026] Preferably, the first area of the plate includes a recording layer on the plate to record the information thereon and a protecting layer on the recording layer to protect the recording layer.

[0027] Preferably, the first and second areas are located on circumferential and central portions of the plate, respectively.

[0028] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:

[0030]FIG. 1 and FIG. 2 illustrate diagrams of a high-density optical disk according to a related art;

[0031]FIG. 3 illustrates a diagram of a thickness of a protecting layer formed by spin coating;

[0032] FIGS. 4 to 6 illustrate cross-sectional views of optical disks according to embodiments of the present invention;

[0033]FIG. 7A and FIG. 7B illustrate cross-sectional views of a process of forming a protecting layer of an optical disk according to the present invention; and

[0034]FIG. 8 illustrates a diagram for protecting a disk surface by a projection of an optical disk according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0035] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0036] FIGS. 4 to 6 illustrate cross-sectional views of optical disks according to embodiments of the present invention.

[0037] Referring to FIGS. 4 to 6, an optical disk according to the present invention includes a plate 40 having a first area enabling to record information thereon and a second area failing to record information thereon and a projection 70 formed on the second area of the plate 40.

[0038] In this case, the first and second areas are located at circumferential and central portions of the plate 40, respectively.

[0039] Moreover, a via hole is formed at the central portion 80 of the plate 40.

[0040] And, the circumferential portion of the plate 40 includes a recording layer 50 formed on the plate to record information thereon and a protecting layer formed on the recording layer 50 to protect the recording layer 50.

[0041] The projection 70 can be formed on an entire surface, as shown in FIG. 4, of the central portion 80, a boundary, as shown in FIG. 5, between the central portion 80 and the circumferential portion, or the central portion 80, as shown in FIG. 6, in part.

[0042] In this case, the projection 70 is formed to have at least one lateral side, which is inclined.

[0043] A flank angle of the projection 70 is preferably formed to be about 90˜160°.

[0044] In this case, the flank angle of the projection 70 means an angle ranging from a surface of the recording layer 10 to the lateral side of the projection 70.

[0045] And, an upper surface of the projection 70 is formed higher than that of the protecting layer 60.

[0046] When the optical disk has a thickness of 1.2 mm, a diameter of 120 mm, a diameter of the via hole of about 15 mm, and a diameter of the central portion of about 44 mm, a height of the projection 70 is preferably about 0.1˜0.6 mm.

[0047] Spin coating for forming the protecting layer 60 on the disk having the projection 70 thereon is explained as follows.

[0048]FIG. 7A and FIG. 7B illustrate cross-sectional views of a process of forming a protecting layer of an optical disk according to the present invention.

[0049] Referring to FIG. 7A, a liquefied UV-hardening resin is dropped on a recording layer 50 at one side of a projection 70 to form a protecting layer 60 thereon.

[0050] Referring to FIG. 7B, once a disk is revolved, a centrifugal force makes the UV-hardening resin coated on the disk from a center to an edge thereof. The coated UV-hardening resin is then hardened by UV light.

[0051] When spin coating is carried out on the UV-hardening resin, the projection 70 having an inclined lateral side enables to prevent the liquefied UV-hardening resin from flowing into the central portion of the disk.

[0052] Moreover, the projection 70 maintains a uniform flow of the liquefied UV-hardening resin on spin coating, thereby enabling to form the protecting layer 60 uniform in thickness.

[0053] On injection of the disk, the projection 70 secures a wide inlet of a resin, thereby facilitating high-density injection.

[0054] Finally, the projection 70, as shown in FIG. 8, prevents the protecting layer 60 of the disk from being directly contacted with a ground, thereby enabling to prevent contamination or scratch on a surface of the protecting layer 60.

[0055] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 

What is claimed is:
 1. An optical disk comprising: a plate having a first area enabling to record information thereon and a second area unable to record the information thereon; and a projection on the second area of the plate.
 2. The optical disk of claim 1, wherein the projection has at least one inclined lateral side.
 3. The optical disk of claim 2, wherein a flank angle of the projection is 90˜160°.
 4. The optical disk of claim 1, wherein the projection is formed on an entire surface of the second area or a portion of the second area.
 5. The optical disk of claim 1, wherein an upper surface of the projection is higher than that of the first area of the plate.
 6. The optical disk of claim 1, wherein a height of the projection is 0.1˜0.6 mm.
 7. The optical disk of claim 1, the first area of the plate comprising: a recording layer on the plate to record the information thereon; and a protecting layer on the recording layer to protect the recording layer.
 8. The optical disk of claim 1, wherein the first and second areas are located on circumferential and central portions of the plate, respectively. 